Lung Health Monitoring Using Digital Spirometry
Product Design
UX / UI Design
For my final year dissertation at Loughborough University I designed, developed, prototyped and tested a lung health monitoring device with the aim to help reduce the strain on hospitals around the world.

Spiro is a handheld spirometer designed to be used at home without a doctor's supervision. It is able to collect lung capacity data and send it to your smartphone from which it can be shared with your doctor.
Arduino C++
User Testing
Design and develop a smart device that improves the understanding of treatment effectiveness through the collection and analysis of health & lifestyle data
Hospital and GPs are bursting at the seams and need relief to focus on treating the most serious conditions.
New and existing technologies could be utilised to monitor non critical patients and the effectiveness of any their ongoing treatments.

1 in 5 in the UK are affected by a long term lung disease
This statistic was collected before the COVID-19 pandemic and is expected significantly rise with the continuing discovery of its long term effects.

91% of the world’s population lives in places where air quality exceeds the WHO guideline limit
4.2 million deaths every year as a result of exposure to ambient air pollution
How is lung health currently monitored?
A key method of determining the health of a patient's lungs is to monitor its capacity. Flow rate measures the amount of air a patient can inhale and exhale. Currently lung conditions are monitored through the use of peak flow meters and routine spirometry tests.

A peak flow meter is an inexpensive instrument which measures the flow rate of exhaled air using simple mechanisms. Despite being very accessible, peak flow devices are poorly utilised with only 10-15% of people successfully completing a full journal.

Spirometers use a suite of sensitive air flow sensors which delivers a very accurate flow rate of inhaled and exhaled air. However due to their complexity, size and cost they are exclusively used at hospitals and require specialist supervision.
User Journey Mapping
From a collection of interviews and questionnaires a user journey map was created to understand why patients weren’t completing their lung health journals using peak flow meters.

By documenting a user’s actions whilst completing a peak flow test at home, the map collated what users were thinking about during each step and how they felt about it. Pain points were highlighted and possible opportunities to solve these were listed.  

• Improving accessibility
• Actionable insights
• Lung health education
• Guided tests
• Encouragement to test daily
• Improving ergonomics
• Inhale and exhale prompts
• Digital logging
Focussed Proposal
Design and develop a smart spirometer/peak flow meter which patients can use at home that also sends collected data to a doctor via a smartphone app. The device must measure either indoor and/or outdoor air quality.

The main aim of the device is to improve completion rates of lung health diaries and educate patients on how to improve improve their lifestyles continuously.
Initial Ideas & Development
To first understand whether a spirometry test could be recreated in a consumer device further research was conducted. Using the relationship between differential pressure and density of a fluid, it is possible to determine its flow rate. Pressure sensors are fairly inexpensive and come in small form factors suitable for portable devices.

Persona and mood boards were used to determine the styling of the device as well as task and experience goals. Using this and the opportunities found in the user journey map a PDS was drafted to aid concept generation.

From approximately 25 designs 4 designs were shortlisted for further development. These 4 designs were rapidly prototyped using foam modelling techniques and then used for initial ergonomics testing. This testing was used as a basis for a user centred concept selection process.  Using 6 criteria including aesthetics, ergonomics and portability, each concept was scored and a weighted average assigned.
Converting Intention Into Action
To get the most accurate and useful results from a lung health test they need to be conducted daily and at roughly the same time every day. For patients to do this they need to get into a routine. This requires a level of commitment and motivation that some users do not posses. Therefore, one of the design challenges here was to foster a behaviour change by embedding this action into their daily routines.

The initial concept was to create a “hub” that would remind you to take a test at a key point during the day, for example, bedtime, wakeup, bathroom routines, breakfast etc. Since these periods usually occur at the same time daily, they are perfect for capturing an accurate snapshot of a patient's lung health. However, simply placing the hub in an environment that the user would be in is not enough to encourage a behavioural change. To do this a concept of restriction was explored - by restricting the user from completing one of these key routines the device will have a much higher chance of being utilised.

Three hub ideas were drafted each using different concepts of restriction. The first was a wireless charger which would restrict power until a test was completed, second was a speaker which would restrict music playback and third was an alarm clock which could only be snoozed by taking a test. Test participants believed the wireless charger concept to be the most effective, stating that charging their phone was something they would do everyday before going to bed.
1. To increase utilisation of the spirometer, the device interrupts the daily routine of charging your phone before going to bed. Whilst idle the spirometer passively measures air quality.
2. The user tries to charge their phone but gets alerted by the hub and a notification to complete a spirometry test first before the charger activates.
3. The user follows the step by step guide on the app and completes the spirometry test to maintain their lung health diary.
4. Once completed, the user will be able to analyse their results and the charger will be activated.
5. The user can rest easy knowing that the process they just completed will not only help their own health but the health of others by sharing data for research if they choose to.
6. Doctors will receive the data over the internet and review it. Suggestions will be sent to the user to either continue as normal, make a lifestyle change or visit the doctor.
Colour, Material & Finish
CMF were important aspects that needed to be considered to ensure the device was aesthetic, reasonably priced and comfortable to use. As it is a medical device that will be placed inside a users bedroom it felt appropriate the design should reflect both. A mood board was created with the intention convey a clinical but ultra modern aesthetic that wouldn’t look out of place inside a home. These aspects were considered before the prototyping stage.
Multiple methods of prototyping enabled multiple aspects of the design to be tested. Since the device sits in both domains of physical and digital, it was necessary to create both to tightly reflect how the end user would use the product and whether any adjustments could be made to improve it.
Solidworks & Keyshot
Initially CAD models were made on Solidworks to explore manufacturing methods, produce engineering drawings, check component fit and create photorealistic renders on Keyshot. This also allowed the design to be iteratively adjusted when problems arose.
FFF 3D Printing
To rapidly create and test prototypes, 3D printing was chosen as it was quick and effortless meaning more attention could be focussed on other aspects of the project. The PLA used in the prints also resembled the characteristics of the production polymer HDPE very well.
C - Code
An MVP of the electronics was created to prove the differential pressure concept. The code was designed to guide the user through a spirometry test and provide FVC and FEV1 values which are the parameters measured in a clinical test. This was done to try and recreate the user experience of the end product.
An Arduino was used to collect the raw data from the pressure and air quality sensors, process it and display the correct values. A custom open body spirometer was 3D printed so that it could be securely connected to the differential pressure sensor and have the flexibility to be used by a tester. The addition of three LEDs and a button would enable the tester to fully interact with the prototype as the end user would.
UX/UI Design
The interactive Sketch app was directly influenced by the electronic prototype using its user flow as a guide to build the screens. The app used a variety of visual aids to make a fluid test experience and displayed results in manor that could be easily understood. Each screen was interactive meaning that during testing the user could click through the prototype as if it was a real app.
Testing & Improvements
The prototypes created were designed to be tested by the target users of the spirometer device. However due to the COVID-19 pandemic access to testers was restricted, therefore, all prototypes had to be either remotely tested or self critiqued for this project. During testing key topics were observed including: functionality, ergonomics, utilisation, user experience and aesthetics
The interactive app prototype was tested by multiple users over zoom meeting which allowed them to remotely control the app through screen sharing. There were many useful takeaways from the testing of this prototype including adding an onboarding process explaining the different features of the app, adjustmenting how data was displayed and the addition of animations during the spirometry test guide instead of static images.
Using a self critiquing method to explore the ergonomics of the device I (50th percentile) was able to test how comfortable the device was to take a spirometry test and use alongside the charging hub. The spirometer was easy to hold in the hand and the angled shaped helped to maintain a good posture during testing. The charging hub was easy to use for a smartphone however charging the spirometer was required a bit more dexterity due to the small gap it sits inside of the hub.
Electronics MVP
The electronic prototype was an all round success; guiding me through the process of taking a spirometry test including repeating the test 3 times for accuracy. The whole test process took around 4 minutes to complete and receive the results. This testing process also allowed for the assessment of the mouthpiece for a 50th percentile user. The addition of LEDs to help the user understand the status of the device and the test was a nice feature. The air quality sensor was also tested separately subjecting it to standard household pollutants such as stove tops, aerosols and candles.  The next step would be to try and implement the system into the body of the spirometer to gain realism of the final use case.
Utilisation Challenge
To test the behavioural change aspect of the design a simple challenge was set for the test users. Using a smart plug connected to a wireless charger and IFTTT complete a small task before going to bed to activate the charger. The task would be validated by completing a google form which in turn would turn on the smart plug. This test was carried out for a week with 3 users and the results were collated in a spreadsheet. The results found that there was an 86% completion rate across the testing period which is a large improvement from the 10-15% utilisation of peak flow meters. However due to the small sample size the test will need to be carried out with more testers before validating the results.
Using the Keyshot renders and the 3D prints the aesthetics were rated using an online survey. The survey consisted of opinions ranging from areas such as aesthetics, build quality, perceived value, complexity etc. Each question in the survey was linked to a balanced bipolar statement which the user could rate. Overall the 5 assessments were resoundingly positive with small recommendations such as changing colours of the body and button icons.
Using a differential pressure sensor to measure vital capacity, The device guides a user through a spirometry test promoting when to inhale and exhale. The device can send this data to the Spiro app over Bluetooth where it can be reviewed and sent to doctors if further action is required.
The hub features a two-level design allowing a user to magnetically snap the spirometer out sight on the bottom level to wirelessly charge, whilst maintaining good accessibility to the wireless phone charger on top. The hub is powered with a standard USB-C cord.
Utilisation is encouraged through the design of the accompanying hub. Intended to be placed on a bedside table, the hub features a smartphone wireless charger. Access to this wireless charger is restricted until a daily spirometry test is taken, thus encouraging the utilisation of the device.
RGB LEDs provide the user with more information when they are not using the accompanying app with the spirometer. The colours help convey tests stages, mistakes and show device status/errors.
Air Quality
Spiro can detect air quality in its surroundings, measuring particulate sizes of 1, 2.5 and 10 microns. Spiro features an optimised vent design which is both functional and aesthetic. Featuring a small aperture size and slimline pattern, the design helps keep large dust particles out to avoid blockages in the sensor.
A cap for the mouthpiece is included with the spirometer to improve hygiene. The cap slides on to the top of the mouthpiece with a push and can be removed with a simple twist and pull.
Inside Out
The internal specifcations of the spirometry device have been carefully considered with manufacturing in mind. The device has been made with simple assembly and disassembly features. Implementation of ribs and snap hooks on the casing, body and mouthpiece help constrain the plastic parts together and fasten the electronic systems securely.
Digital Guidance
The Spiro app helps guide users through their spirometry tests automatically; detecting each stage of respiration the user is undergoing. These detections are converted into predictive instructions walking the user through the process smoothly to get average FVC and FEV1 results. Each daily session can be paired with notes and can also be sent to doctors over the internet if further action is required.
Data Visualised
Results are displayed in graph formats alongside air quality data to help the user visually understand their current health and treatment effectiveness. Due to the complex nature of the data, educational tips are provided helping the user understand technical acronyms such as FVC, FEV1 and PM. These tips also inform the user about how these values translate to their health.